1. Field of the Invention
The present invention relates to water filters for sewer system drains. More particularly, it is related to flow through filters for stormwater or wastewater catch basins or containment vessels having a gravity flow outlet drain. The invention is disposed at a sewer system inlet catch basin and removes trash, sediment, liquid hydrocarbons, and free metal ions that are suspended, floating, or dissolved in the water.
2. Description of the Prior Art
Stormwater and wastewater drain guards for sewer system inlets normally include simply a grate to prevent the influx of large debris. The terms xe2x80x9cstorm sewer,xe2x80x9d xe2x80x9cdrain,xe2x80x9d or xe2x80x9cdedicated filter basinxe2x80x9d are intended to include a sewer that intakes or processes stormwater, surface water, street wash, wastewater, industrial runoff, and other effluent waters or drainage but excludes sanitary wastewater.
Federal regulations and state standards now mandate the removal of sediment and hydrocarbons from stormwater runoff or wastewater before it is released into the environment. However, a further component of stormwater or wastewater which it is also desirable to remove, but without substantially changing the pH of the water, is free metal ions.
One commercially available system for partially achieving these results, used in connection with new and existing stormwater drainage sewer inlets, is a contaminant absorbing internal trough apparatus. The trough area of the apparatus is disposed in the drain inlet and provided for the retention of a removable and replaceable absorbent filter material in a filter cartridge which collects petroleum pollutants or liquid hydrocarbons. It is claimed that the trough apparatus, when compared to oil/water separators, is the only known accepted alternative apparatus for removing petroleum pollutants and sediments but which may be installed at a fraction of the cost of oil/water separators with lower maintenance costs.
The described prior art apparatus, however, can only function in a one-way direction of water flow throughput, and it does not remove free metal ions. The present invention achieves the same claimed results of the prior art with different and equally inexpensive, if not less costly, apparatus with comparably low maintenance costs, as well as removing metal ions, and, especially important, it is adoptable for double direction flow.
The present invention is a flow through drain filter assembly for a stormwater or wastewater catch basin forming a sewer system inlet and having a gravity flow basin outlet drain. The filter is a double flow design whereby the water intake to the basin can either be from the top periphery around the basin, or from a side inlet pipe, and the outlet for the basin can either be a side outlet or bottom drain. The filter assembly is formed for excluding floating trash and capturing sediment, liquid hydrocarbons, and free metal ions washed into the sewer system inlet by stormwater or wastewater.
The filter assembly comprises at least four concentric spaced apart screens disposed in the assembly and arranged to filter water flowing to the outlet. The assembly includes a water intake trash exclusion screen and a water exit screen and first and second middle screens. The assembly includes deionizing resin beads disposed between the water exit screen and the second middle screen, and particulate filter material which is hydrophobic and a liquid hydrocarbon absorber disposed between the first and second middle screens. Water flowing into the sewer system inlet passes through the filter assembly, and trash is separated from the stormwater by the trash exclusion screen. Sequentially, suspended sediment washed thereinto therewith is precipitated to the bottom of the basin between the trash exclusion screen and the first middle screen; liquid hydrocarbons suspended in the stormwater are absorbed by contact with the particulate matter disposed between the first and second middle screens; and free ions are deionized by contact with the resin beads disposed between the second middle and the exit screens by the outflow movement of the stormwater in the basin through the screens to the outlet. As a result, trash, sediment, hydrocarbons, and free ions are sequentially separated, precipitated, absorbed, and deionized by the assembly and its ingredients and prevented from flowing through the outlet and into the sewer system.
The present invention also includes the method for removing trash, sediment, liquid hydrocarbons, and free metal ions from stormwater or wastewater flowing into sewer system inlets having catch basins with an outlet drain. The method comprises the steps of interposing a filter in the catch basin between the sewer system inlet and the outlet drain, then sequentially removing from the water flow through the filter: trash in the water flow by a water intake trash exclusion screen; sediment in the water flow by interposing a water permeable sediment barrier between concentric first and second middle screens in the filter; liquid hydrocarbons in the water flow by interposing a particulate filter which is hydrophobic and liquid hydrocarbon absorbent between the first and second middle screens; and metal ions by interposing in the water flow a deionizing resin bead barrier between the second middle screen and a water exit screen. The trash screen, the sediment barrier, the liquid hydrocarbon particulate filter, and the deionizing resin bead barrier are arranged in concentric relation for effecting the sequential element removal.
It is therefore an important object of the present invention to provide a new and novel drain filter for a sewer system inlet which separates out trash and sediment, captures liquid hydrocarbons, and removes free metal ions that are carried along in, or that are suspended or floating in, or that are present in solution, in stormwater runoff or wastewater.
It is another object of the present invention to provide an inexpensive, long-lived, light-weight, stormwater or wastewater drain filter for a catch basin forming a sewer system inlet which can be removed and/or disassembled for cleaning, installation of fresh filter material, and removal of saturated filter material for regeneration.
It is a further object of the present invention to provide a stormwater or wastewater drain filter for a sewer system inlet which sequentially excludes trash, precipitates sediment, and captures liquid hydrocarbons and metal ions floating or carried along, in stormwater runoff or wastewater and which can be installed in conjunction with either presently existing or new sewer system inlets or installed in dedicated catch basins for water treatment
It is still another object of the present invention to provide a universal stormwater or wastewater double flow drain filter which sequentially removes trash, sediment, liquid hydrocarbons, and metal ions which can be installed in sewer inlet catch basins having water inflow to the filter either through the top center or from the sides of the basin and an outflow drain to a sewer system disposed either at the bottom or the sides thereof.
And it is yet a further object of the present invention to provide a new and novel method for sequentially removing trash, sediment, liquid hydrocarbons, and free metal ions from catch basins having an inflow to the filter either through the center or from the sides thereof and an outflow drain to a sewer system disposed either at the bottom or sides thereof.
Other objects and advantages of the present invention win become apparent when the apparatus and method of the present invention are considered in conjunction with the accompanying drawings.